SAN DIEGO — Thinking of weight gain simply as the sum of “calories in minus calories out” doesn't cover a minority of obese patients whose dietary records show reasonable caloric balance but who can't seem to lose weight, Dr. Scott R. Rigden said.

These patients may show dietary records reflecting an intake of 1,800–1,900 calories per day, and often say they're tired of health care providers thinking that they're lying in their food diaries because they haven't lost weight, he said at a symposium on obesity sponsored by the American Society of Bariatric Physicians.

“I really think there are a lot of people with special issues, with switched-off metabolisms, that don't fit that model” of calories in/calories out, said Dr. Rigden, a Chandler, Ariz. family physician who has practiced bariatrics since 1976. “What has shut down their metabolism, and how do we turn it back on?”

To help these patients, think in terms of the following five subcategories, and tailor dietary and lifestyle recommendations accordingly, he suggested:

▸ Carbohydrate sensitivity. Dr. Rigden defined a patient with carbohydrate sensitivity as one whose genetic makeup produces a rapid spike of glucose after consuming simple carbohydrates and sugars. That glucose spike in turn triggers a spike in insulin and associated metabolic cellular messengers that tell the body to store fat, not burn it. The insulin spike also causes a rapid and uncomfortable drop in glucose that motivates the person to seek more carbohydrates and sugars to remedy the discomfort.

These patients do not yet meet criteria for metabolic syndrome. They have normal fasting insulin and glucose levels and are not hypertensive. “They often have stellar labs, yet a terrible lifelong obesity issue,” Dr. Rigden said. He has devised a nine-item questionnaire focusing on eating and exercise habits to identify this subgroup.

A four-step treatment plan starts with behavior modification to change the patient's relationship with food and an exercise program with at least 150 minutes of moderate aerobic exercise weekly. The third step emphasizes adequate water intake of at least 64 ounces per day—“perhaps the most overlooked part of a weight management program,” he added.

Dietary intervention is the fourth step, starting with a soy protein powder meal replacement plan and switching to a low glycemic diet (which he also called a modified Mediterranean diet) after the patient loses 5%–10% of initial weight.

▸ Metabolic syndrome. Diagnostic criteria for metabolic syndrome include an elevated waist circumference, triglyceride level above 150 mg/dL, an HDL level less than 40 mg/dL for males or less than 50 mg/dL for females, blood pressure above 130/85 mm Hg, and fasting blood sugar above 100 mg/dL.

In these patients, foods that have a high glycemic index cause blood sugar levels to plummet, boosting cravings for more high-glycemic foods such as sugars and fat, Dr. Rigden said. He recommends what he calls a “caveman or cavewoman” diet of low-fat, nonstarchy foods that he spells out for patients. After losing 10% of body weight, they switch to the low glycemic diet.

He also recommends nutraceutical medical food with slow-release, amylose-resistant starch, and soluble fiber in the form of 15 g per day of guar gum. Micronutrient support may be the most undervalued component of therapy for these patients, he added.

▸ Hormonal imbalances. Questionnaires and physical examinations will help identify the endocrine problems that are contributing to recalcitrant obesity in these patients, Dr. Rigden said. Most will be due to clinical or subclinical hypothyroidism. “This is probably the No. 1 hormonal imbalance that I see in people who have switched-off metabolism,” he said.

Other hormonal problems to consider in women include polycystic ovarian syndrome or a sex hormone imbalance with estrogen dominance. Tailor treatment to the particular problem, he said.

▸ Food hypersensitivity. These are not true allergies but hypersensitivities that can lead to switched-off metabolism, Dr. Rigden said. Wheat and milk are the most common reactors, with delayed physical findings—such as boggy nasal mucosa, mouth breathing, wheezing, eczema, or urticaria—appearing 24–72 hours after ingestion. IgG levels may help identify offending foods.

Eliminate the problem foods from the patient's diet for 90–120 days, then perform a careful challenge with the food, and urge minimal intake of problem foods thereafter, he suggested.

▸ Chronic illness. Some patients complain that they never had weight problems until diagnosed with chronic fatigue syndrome, fibromyalgia, lupus, rheumatoid arthritis, irritable bowel syndrome, or other chronic problems.

In these patients, the liver's detoxification abilities are impaired, leaving higher levels of toxins in the body that compromise fat metabolism, he said. Eliminate common dietary allergens such as gluten for 4 weeks and support liver detoxification with a hypoallergenic rice-based protein formula containing selected nutrients, Dr. Rigden recommended.

He disclosed that he has no association with the companies that make the products he discussed.

With Recalcitrant Obesity, Think in Subcategories